Where cold water is introduced into the tank of a toilet, the tank itself is cooled thereby and in periods of high humidity, such as summertime, water condenses on the exterior surfaces of the tank and may accumulate to the extent of dripping on the floor, which can be both unsightly and damaging.
A solution to the problem is shown in the patent to Armstrong, U.S. Pat. No. 2,652,874. That patent provided a textile cover for a toilet tank which, while not preventing condensation, acted to "blot up" the moisture condensing on the tank and thereby prevented dripping. During the night when the toilet was not used, the water in the tank would warm up and as a result, the moisture in the cover evaporated so that by the next morning it was dry, and ready to begin absorbing condensate.
A problem often encountered with the type of toilet tank cover shown in the Armstrong patent, was that of maintaining the cover in position on the toilet tank. As the cover absorbed moisture, it became heavier and often sagged in unsightly folds because of the weight, and sometimes because of the stretching of the textile material. Means such as sewing in elastic along the edges, etc., have been tried but were only partially successful in overcoming the problem.